As a known method for infusing a medical fluid or the like into a patient, an outer needle (catheter) is inserted and placed in the human body to infuse the fluid thereinto. As a device for insertion of the outer needle, indwelling needles have been known to insert and place the outer needle using the inner needle incorporated inside the outer needle.
The inner needle is discarded after placement of the outer needle, but it takes a certain time before it is discarded. Therefore, as to an indwelling needle without a safety mechanism, there is a risk of the inner needle, after use, pricking the human body again during this period or a so-called needlestick accident occurring. Since, in this case, the inner needle might be contaminated with the HIV virus or the like, even a needlestick accident alone has been regarded as a cause of virus infection.
In order to solve this problem, many types of safety indwelling needles which avoid a needlestick accident by confining the inner needle immediately after use have been developed. For example, a technology disclosed in Japanese Patent Application Laid-Open Hei 3 No.15481 is directed to a cannula inserting device for retracting a needle hub, which might cause a needlestick, into a hollow handle by means of an urging means.
Alternatively, Japanese Patent Application Laid-Open No.2000-167051, etc. presented a technology relating to a safety indwelling needle (puncture device) having a retracting mechanism for retracting the inner needle immediately after use into the holder sleeve. These technologies present techniques whereby the inner needle is retracted by means of an urging means when an actuator is operated in a peripheral direction of the holder sleeve so that the actuator is fixed to cutout formed in the holder sleeve.
Since the device disclosed in Japanese Patent Application Laid-Open Hei 3 No.15481 employs a compression spring as the urging means, the outer and inner needles should be assembled by passing them through the interior of the compression spring. Hence extra steps are needed in order for the needle tip not to come into contact with the inner side of the compression spring.
With the safety indwelling needle, disclosed in Japanese Patent Application Laid-Open No.2000-167051, etc., in order to prevent the inner needle once retracted, from being re-exposed, the actuating element (actuating portion) needs to be moved in the peripheral direction so that the actuating element (actuating portion) will be fixed to the cutout (engaging window) formed in the holder sleeve (outer sleeve) In this case, the following problems will occur. First, the handedness problem, whereby the actuation is hard to make depending on the left or right handedness. Further, since one more action needs to be made to fix the actuating element after retraction of the inner needle (needle portion), this disturbs the quick prevention against re-exposure of the inner needle (needle portion). Thus, there have been some problems with prevention against re-exposure of the inner needle (needle portion). Further, since the actuating element (actuating portion) is exposed outside the holder sleeve (outer sleeve), there has been a risk of the actuating element (actuating portion) coming away from the cutout (engagement window) due to an external force so as to cause an event of the inner needle (needle portion) being exposed.
It is therefore an object of the present applicant to provide a technology for a safety indwelling needle which is easy to assemble and prevents the inner needle from being re-exposed by an external force.
Particularly, the object of the inventions described in the first to fifth features is to provide a safety indwelling needle which can prevent the inner needle from being re-exposed by an external force.